The invention relates to a method for in situ upgrading of heavy hydrocarbon during a xe2x80x9chuff and puffxe2x80x9d or cyclic pressurizing and production technique.
Very large reserves of heavy hydrocarbons exist worldwide which could serve as an excellent source of useful hydrocarbons should an acceptable method of exploiting and producing these resources be developed.
A number of alternative methods have been proposed for producing such heavy hydrocarbons. These methods include the use of multiple wells including parallel horizontal wells drilled into water formations beneath the heavy hydrocarbon, and injection of various additives through the horizontal wells so as to assist in production from a separate well drilled into the producing formation. Unfortunately, this method requires the actual drilling of a potentially large number of wells for production from a single well, with the attendant increase in cost of labor and equipment, and also results in large amounts of potentially expensive additives being injected through the horizontal wells.
xe2x80x9cHuff and puffxe2x80x9d or cyclic pressurizing and production techniques are also known wherein a well is pressurized for a period of time, and then allowed to produce. This method can provide enhanced production for certain wells. However, with particularly heavy hydrocarbons, this technique certainly leaves room for improvement.
In light of the foregoing, it is clear that the need remains for an improved method for producing heavy hydrocarbons.
It is therefore the primary object of the present invention to provide a process for in situ upgrading of a heavy hydrocarbon whereby production is enhanced.
It is a further object of the present invention to provide such a process wherein the need for additives is reduced, and such additives can be recycled.
It is a still further object of the present invention to provide such a process wherein the hydrocarbon product when produced has been upgraded.
Other objects and advantages of the present invention will appear hereinbelow.
In accordance with the present invention, the foregoing objects and advantages have been readily attained.
According to the invention, a process is provided for in situ upgrading of a heavy hydrocarbon, which process comprises the steps of (a) positioning a well in a reservoir containing a heavy hydrocarbon having an initial API gravity of less than or equal to about 8; (b) injecting a light solvent into said well at reservoir conditions so as to provide an upgraded hydrocarbon in said reservoir, said upgraded hydrocarbon having an improved API gravity greater than said initial API gravity; and (c) producing said upgraded hydrocarbon from said well.